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    <script>
        function sum() {
            var s = 10 + 20;
            return s;
        }
        var num = sum();
        console.log(num);
        console.log({} == {});
        function fn() {
            return {};
        }
        var a = fn();
        var b = fn();
        console.log(a == b);
        function fun(){
            var demo = {};
            function foo(){
                return demo;
            }
            return foo;
        }
        var fn1 = fun();
        var demo1 = fn1();
        var demo2 = fn1();
        console.log(demo1 == demo2);
        
    </script>
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